Acknowledgment of uplink orthogonal frequency division multiple access transmission

ABSTRACT

A first communication device receives an uplink orthogonal frequency multiple access (OFDMA) transmission. The uplink OFDMA transmission includes respective transmissions from multiple second communication devices, and the respective transmissions from the multiple second communication devices include indications of respective acknowledgment policies corresponding to the respective transmissions from the multiple second communication devices. The first communication device generates one or more acknowledgment physical layer (PHY) data units to acknowledge at least a portion of the uplink OFDMA transmission, where the one or more acknowledgment PHY data units do not comply with at least one of the acknowledgment policies corresponding to the uplink OFDMA transmission. The first communication device transmits the one or more acknowledgment PHY data units to acknowledge the at least the portion of the uplink OFDMA transmission.

CROSS-REFERENCES TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.15/332,548, now U.S. Pat. No. 10,256,961, entitled “Acknowledgment ofUplink Orthogonal Frequency Division Multiple Access Transmission,”filed on Oct. 24, 2016, which claims the benefit of U.S. ProvisionalApplication No. 62/245,684, entitled “ACK Policy in UL OFDMA,” filed onOct. 23, 2015. Both of the applications referenced above areincorporated herein by reference in their entireties.

FIELD OF THE DISCLOSURE

The present disclosure relates generally to communication networks and,more particularly, to acknowledging an uplink multi-user transmission ina wireless local area network (WLAN).

BACKGROUND

Wireless local area network (WLAN) technology has evolved rapidly overthe past two decades. Development of WLAN standards such as theInstitute for Electrical and Electronics Engineers (IEEE) 802.11a,802.11b, 802.11g, 802.11n, and 802.11ac Standards has improvedsingle-user peak data throughput. For example, the IEEE 802.11b Standardspecifies a single-user peak throughput of 11 megabits per second(Mbps), the IEEE 802.11a and 802.11g Standards specify a single-userpeak throughput of 54 Mbps, the IEEE 802.11n Standard specifies asingle-user peak throughput of 600 Mbps, and the IEEE 802.11ac Standardspecifies a single-user peak throughput in the gigabits per second(Gbps) range. Future standards promise to provide even greaterthroughput, such as throughputs in the tens of Gbps range.

SUMMARY

In an embodiment, a method for communicating in a wireless communicationnetwork includes: receiving, at the first communication device, anuplink orthogonal frequency multiple access (OFDMA) transmission. Theuplink OFDMA transmission includes respective data units from multiplesecond communication devices, and the respective data units includerespective indications of respective acknowledgment policiescorresponding to the respective data units. A first acknowledgementpolicy among the respective acknowledgment policies indicates that afirst data unit, among the respective data units, is to be acknowledgedprior to any subsequent transmission from any of the multiple secondcommunication devices. A second acknowledgement policy among therespective acknowledgment policies indicates that a second data unit,among the respective data units, is to be acknowledged only after thecorresponding second communication device has transmitted a subsequentdata unit in a subsequent uplink OFDMA transmission. The method alsoincludes: generating, at the first communication device, anacknowledgment physical layer (PHY) data unit to acknowledge at leastthe first data unit and the second data unit; and transmitting, with thefirst communication device, the acknowledgment PHY data unit in adownlink transmission to acknowledge at least the first data unit andthe second data unit. Transmitting the acknowledgment PHY data unitincludes one of: i) transmitting the downlink transmission prior to anysubsequent transmission from any of the multiple second communicationdevices, or ii) transmitting the downlink transmission only afterreceiving the subsequent uplink OFDMA transmission.

In another embodiment, a wireless communication device comprises: awireless network interface device associated with a first communicationdevice. The wireless network interface device includes one or moreintegrated circuits (ICs), and the one or more ICs are configured to:receive an uplink orthogonal frequency multiple access (OFDMA)transmission. The uplink OFDMA transmission includes respective dataunits from multiple second communication devices, and the respectivedata units include respective indications of respective acknowledgmentpolicies corresponding to the respective data units. A firstacknowledgement policy among the respective acknowledgment policiesindicates that a first data unit, among the respective data units, is tobe acknowledged prior to any subsequent transmission from any of themultiple second communication devices. A second acknowledgement policyamong the respective acknowledgment policies indicates that a seconddata unit, among the respective data units, is to be acknowledged onlyafter the corresponding second communication device has transmitted asubsequent data unit in a subsequent uplink OFDMA transmission. The oneor more ICs are further configured to: generate an acknowledgmentphysical layer (PHY) data unit to acknowledge at least the first dataunit and the second data unit, and transmit the acknowledgment PHY dataunit in a downlink transmission to acknowledge at least the first dataunit and the second data unit. Transmitting the acknowledgment PHY dataunit includes one of: i) transmitting the downlink transmission prior toany subsequent transmission from any of the multiple secondcommunication devices, or ii) transmitting the downlink transmissiononly after receiving the subsequent uplink OFDMA transmission.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an example wireless local area network(WLAN), according to an embodiment.

FIG. 2 is a diagram of an orthogonal frequency division multiple access(OFDMA) physical layer (PHY) data unit, according an embodiment.

FIG. 3 is a diagram of an example prior art acknowledgement procedure.

FIG. 4 is a diagram of an example frame exchange corresponding to anuplink OFDMA transmission, according to an embodiment.

FIG. 5 is a diagram of an example frame exchange corresponding to anacknowledgment of an uplink OFDMA transmission, according to anembodiment.

FIG. 6 is a diagram of an example frame exchange corresponding to ablock acknowledgment of multiple uplink OFDMA transmissions, accordingto an embodiment.

FIG. 7 is a diagram of an example frame exchange corresponding to anacknowledgment of an uplink OFDMA transmission, according to anembodiment.

FIG. 8 is a diagram of another example frame exchange corresponding toan acknowledgment of an uplink OFDMA transmission, according to anotherembodiment.

FIG. 9 is flow diagram of an example method for acknowledging an uplinkOFDMA transmission, according to an embodiment.

DETAILED DESCRIPTION

In embodiments described below, a wireless network device such as anaccess point (AP) of a wireless local area network (WLAN) transmits andreceives data streams to/from one or more client stations. In someembodiments, the AP and the client stations utilize one or moremulti-user (MU) modes in which multiple independent data streams aretransmitted simultaneously to/from multiple client stations. MUtransmission to, or by, multiple client stations is performed using MUmultiple input multiple output (MU-MIMO) transmission in whichrespective spatial streams are used for transmission to, or by,respective ones of the multiple client stations, and/or using orthogonalfrequency division multiple access (OFDMA) transmission in whichrespective frequency sub-channels of a communication channel are usedfor simultaneous transmission to, or by, respective ones of multipleclient stations, in various embodiments. In some embodiments, a downlinktrigger frame transmitted by the AP triggers an uplink MU transmissionfrom the client stations. In some embodiments, in response to receivingan uplink MU transmission from the client stations, the AP transmits oneor more acknowledgement frames via MU downlink transmission.

FIG. 1 is a block diagram of an example wireless local area network(WLAN) 10, according to an embodiment. The WLAN 10 supports downlink(DL) and uplink (UL) single-user (SU) communication between an accesspoint (AP) and each of a plurality of client stations. In an embodiment,the WLAN 10 also supports DL and/or UL orthogonal frequency divisionmultiple access (OFDMA) communication between the AP and at least someof the client stations. In some embodiments, the WLAN 10 additionally oralternatively supports DL and/or UL multiuser (MU) multiple-input andmultiple-output (MIMO) communication between the AP and at least some ofthe client stations.

The WLAN 10 includes an AP 14, and the AP 14, in turn, includes a hostprocessor 15 coupled to a network interface device 16. The networkinterface device 16 includes a medium access control (MAC) processingunit 18 and a physical layer (PHY) processing unit 20. The PHYprocessing unit 20 includes a plurality of transceivers 21, and thetransceivers 21 are coupled to a plurality of antennas 24. Althoughthree transceivers 21 and three antennas 24 are illustrated in FIG. 1,the AP 14 includes other suitable numbers (e.g., 1, 2, 4, 5, etc.) oftransceivers 21 and antennas 24 in other embodiments. In an embodiment,the network interface device 16 includes one or more integrated circuit(IC) devices. For example, at least some of the functionality of the MACprocessing unit 18 and at least some of the functionality of the PHYprocessing unit 20 are implemented on a single IC device, according toan embodiment. As another example, at least some of the functionality ofthe MAC processing unit 18 is implemented on a first IC device, and atleast some of the functionality of the PHY processing unit 20 isimplemented on a second IC device, according to an embodiment.

The WLAN 10 includes a plurality of client stations 25. Although fourclient stations 25 are illustrated in FIG. 1, the WLAN 10 includes othersuitable numbers (e.g., 1, 2, 3, 5, 6, etc.) of client stations 25 invarious scenarios and embodiments. The client station 25-1 includes ahost processor 26 coupled to a network interface device 27. The networkinterface device 27 includes a MAC processing unit 28 and a PHYprocessing unit 29. The PHY processing unit 29 includes a plurality oftransceivers 30, and the transceivers 30 are coupled to a plurality ofantennas 34. Although three transceivers 30 and three antennas 34 areillustrated in FIG. 1, the client station 25-1 includes other suitablenumbers (e.g., 1, 2, 4, 5, etc.) of transceivers 30 and antennas 34 inother embodiments. In an embodiment, the network interface device 27includes one or more IC devices. For example, at least some of thefunctionality of the MAC processing unit 28 and at least some of thefunctionality of the PHY processing unit 29 are implemented on a singleIC device, according to an embodiment. As another example, at least someof the functionality of the MAC processing unit 28 is implemented on afirst IC device, and at least some of the functionality of the PHYprocessing unit 29 is implemented on a second IC device, according to anembodiment.

In an embodiment, one or more of the client stations 25-2, 25-3, and25-4 has a structure the same as or similar to the client station 25-1.In these embodiments, the client stations 25 structured the same as orsimilar to the client station 25-1 have the same or different numbers oftransceivers and antennas. For example, the client station 25-2 has onlytwo transceivers and two antennas (not shown), according to anembodiment.

In various embodiments, the PHY processing unit 20 of the AP 14 isconfigured to generate downlink data units having formats describedherein. The transceiver(s) 21 is/are configured to transmit thegenerated data units via the antenna(s) 24. Similarly, thetransceiver(s) 21 is/are configured to receive the data units via theantenna(s) 24. The PHY processing unit 20 of the AP 14 is configured toprocess received uplink data units having formats described herein,according to various embodiments.

In various embodiments, PHY processing units of the client stations 25(e.g., the PHY processing unit 29 of the client device 25-1) areconfigured to generate uplink data units having formats describedherein. The transceiver(s) 30 is/are configured to transmit thegenerated data units via the antenna(s) 34. Similarly, thetransceiver(s) 30 is/are configured to receive downlink data units viathe antenna(s) 34. The PHY processing unit 29 of the client device 25-1is configured to process received downlink data units having formatsdescribed hereinafter, according to various embodiments.

In an embodiment, when operating in single-user mode, the AP 14transmits a data unit to a single client station 25 (DL SUtransmission), or receives a data unit transmitted by a single clientstation 25 (UL SU transmission), without simultaneous transmission to,or by, any other client station 25. When operating in multi-user mode,the AP 14 transmits a data unit that includes multiple data streams formultiple client stations 25 (DL MU transmission), or receives data unitssimultaneously transmitted by multiple client stations 25 (UL MUtransmission), in an embodiment. For example, in multi-user mode, a dataunit transmitted by the AP includes multiple data streams simultaneouslytransmitted by the AP 14 to respective client stations 25 usingrespective spatial streams allocated for simultaneous transmission tothe respective client stations 25 and/or using respective sets of OFDMtones corresponding to respective frequency sub-channels allocated forsimultaneous transmission to the respective client stations.

FIG. 2 is a diagram of a physical layer (PHY) data unit 200 that the AP14 is configured to transmit to one or more client stations 25 (e.g.,the client stations 25-1), according to an embodiment. In an embodiment,one or more client stations 25 (e.g., the client stations 25-1) are alsoconfigured to transmit data units the same as or similar to the PHY dataunit 200 to the AP 14. The PHY data unit 200 occupies a 20 MHzbandwidth. PHY data units similar to the PHY data unit 200 occupy othersuitable bandwidth such as 40 MHz, 80 MHz, 160 MHz, 320 MHz, 640 MHz,for example, or other suitable bandwidths, in other embodiments.

In various embodiments and/or scenarios, the PHY data unit 200 is adownlink (DL) orthogonal frequency division multiple access (OFDMA) unitin which independent data streams are transmitted to multiple clientstations 25 using respective sets of OFDM tones and, in some casesrespective spatial streams, allocated to the client stations 25.Similarly, in various embodiments and/or scenarios, the PHY data unit200 is an uplink (UL) OFDMA data unit transmitted by a particular clientstation 25 as part of an OFDMA uplink transmission by multiple clientstations 25, wherein each of the multiple client stations 25 transmitsdata using a respective set of OFDM tones and, in some cases, respectiveone or more spatial streams, allocated to the client station 25. Forexample, in an embodiment, available OFDM tones (e.g., OFDM tones thatare not used as DC tones, guard tones, etc.) are allocated amongmultiple blocks that each correspond to a respective one of the (ormore, e.g., if also using MU-MIMO) client stations 25 for transmissionof data to, or by, the one or more of the client stations 25. In anembodiment, allocation of OFDM tones is performed using resource units(RUs). In an embodiment, an RU is a unit of frequency resources in anOFDMA data unit that can be allocated. For example, in an embodiment, anRU corresponds to K OFDM tones, wherein K is a suitable integer greaterthan zero. As just an illustrative example, K=26, according to anillustrated embodiment. Accordingly, a basic resource unit includes 26OFDM tones, in this embodiment. An RU allocated to a client station 25(or allocated to a multi-user group of client stations 25, e.g., ifMU-MIMO is being utilized) includes an integer number of basic resourceunits. Therefore, the RU includes a number of OFDM tones that is aninteger multiple of 26 OFDM tones, such as 26 OFDM tones, 52 OFDM tones,78 OFDM tones, etc., in this embodiment. In another embodiment, K is anysuitable integer other than 26, and an RU therefore includes a suitablenumber of OFDM tones other than 26. For example, in various embodiments,K is 52, 78, 104, 130, etc. As another example, in various embodiments,K is 2, 4, 8, 16, etc. In some embodiments, a WLAN may utilize RUs withdifferent sizes K in different situations. For example, in anembodiment, a WLAN may utilize RUs with different sizes K when utilizingcommunication channels of different bandwidths.

The PHY data unit 200 includes a preamble including a legacy shorttraining field (L-STF) 205, a legacy long training field (L-LTF) 210, alegacy signal field (L-SIG) 215, a repeated legacy signal field (RL-SIG)220, a first HE signal field (HE-SIG-A) 225, a second HE signal field(HE-SIG-B) 230, an HE short training field (HE-STF) 235, M HE longtraining fields (HE-LTFs) 240, where M is a suitable positive integer.In some embodiments and/or scenarios, M corresponds to a number ofspatial streams utilized in the PHY data unit 200. In some embodimentsand/or scenarios, M is greater than the number of spatial streamsutilized in the PHY data unit 200. In some embodiments and/or scenarios,the PHY data unit 200 also includes a data portion 245. In someembodiments and/or scenarios, the PHY data unit 200 omits the dataportion 245 (e.g., for a null data packet (NDP), etc.).

In some embodiments and/or scenarios, the preamble 202 omits one or moreof the fields 205-240. For example, the preamble 202 omits one or moreof the HE-SIG-A 225 and the HE-SIG-B 230, in an embodiment. In someembodiments, the preamble 202 includes additional fields not illustratedin FIG. 2.

Each of the L-STF 205, the L-LTF 210, the L-SIG 215, the RL-SIG 220,HE-SIG-A 225, the HE-SIG-B 230, the HE-STF 235, and the M HE-LTFs 240comprises one or more OFDM symbols. The HE-SIG-A 225 and the HE-SIG-B230 is each individually encoded to generate the respective number ofOFDM symbols, in an embodiment. As merely an example, in an embodiment,the HE-SIG-A 225 comprises two OFDM symbols the HE-SIG-B 230 comprisesone OFDM symbol. As merely another example, in another embodiment, theHE-SIG-A 225 comprises one OFDM symbol and the HE-SIG-B 230 comprisestwo OFDM symbols. As yet another example, in an embodiment, the HE-SIG-A225 comprises two OFDM symbols and the HE-SIG-B 230 comprises a variablenumber of OFDM symbols. In an embodiment in which the HE-SIG-B 230comprises a variable number of OFDM symbols, the particular number ofHE-SIG-B 230 OFDM symbols in the PHY data unit 200 is indicated in theHE-SIG-A 225. As yet another example, in an embodiment, the HE-SIG-A 225comprises two OFDM symbols and the HE-SIG-B 230 is omitted.

In the embodiment of FIG. 2, the PHY data unit 200 includes one of eachof the L-STF 205, the L-LTF 210, the L-SIG 215, RL-SIG 220 the HE-SIG-A225, and HE-SIG-B in each of a plurality of component channels. In anembodiment, each component channel occupies a bandwidth of 20 MHz. Inother embodiments, each component channel occupies another suitablebandwidth (e.g., 1 MHz, 2 MHz, 5 MHz, 10 MHz, etc.). In an embodiment,the PHY data unit 200 occupies a cumulative bandwidth of 80 MHz. Inother embodiments in which a data unit similar to the PHY data unit 200occupies a another suitable cumulative bandwidth other than 80 MHz(e.g., 40 MHz, 160 MHz, 320 MHz, etc.), each of the L-STF 205, the L-LTF210, the L-SIG 215, the RL-SIG 220, HE-SIG-A 225, and HE-SIG-B 230 isrepeated over a corresponding number of 20 MHz sub-bands of the wholebandwidth of the data unit, in an embodiment. For example, in anembodiment, the data unit occupies an 160 MHz bandwidth and,accordingly, includes eight of each of the L-STF 205, the L-LTF 210, theL-SIG 215, the RL-SIG 220, the HE-SIG-A 225, and the HE-SIG-B 230.

In an embodiment, each of the HE-SIG-A 225 and the HE-SIG-B 230generally carries information about the format of the PHY data unit 200,such as information needed to properly decode at least a portion of thePHY data unit 200, in an embodiment. In an embodiment in which the PHYdata unit 200 is a multi-user data unit, HE-SIG-A 225 carriesinformation commonly needed by multiple intended receivers of the PHYdata unit 200. In some embodiments, HE-SIG-A 225 additionally includesinformation for client stations 25 that are not intended receivers ofthe PHY data unit 200, such as information needed for medium protectionfrom the client stations 25 that are not receivers of the PHY data unit200. On the other hand, HE-SIG-B 230 carries user-specific informationindividually needed by each client station 25 that is an intendedrecipient of the PHY data unit 200, in an embodiment. In an embodiment,HE-SIG-A 225 includes information needed to properly decode HE-SIG-B230, and HE-SIG-B 230 includes information needed to properly decodedata streams in the data portion 245 of the PHY data unit 200. In someembodiments and/or scenarios, however, HE-SIG-A 225 includes at leastsome of the information needed to decode the data portion 245, andHE-SIG-B 230 is omitted from the PHY data unit 200 in at least some suchembodiments. In at least some embodiments and scenarios in which the AP14 is the intended recipient of the PHY data unit 200 (i.e., when thePHY data unit 200 is an uplink data unit), information needed toproperly decode the data portion of the PHY data unit 200 is known apriori to the intended recipient of the PHY data unit 200 and need notbe included in the preamble of the PHY data unit 200. In some suchembodiments, the HE-SIG-B 230 is omitted from the PHY data unit 200.

In some embodiments, specific information included in the HE-SIG-A 225and/or in the HE-SIG-B 230 depends on the mode of transmission of thePHY data unit 200. For example, information included in the HE-SIG-A 225and/or information included in the HE-SIG-B 230 depends on mode oftransmission of the PHY data unit 200, in an embodiment. In anembodiment, different information is included in the HE-SIG-A 225 whenthe PHY data unit 200 is a downlink data unit as compared to informationincluded in the HE-SIG-A 225 when the PHY data unit 200 is an uplinkdata unit. Additionally or alternatively, different information isincluded in the HE-SIG-A 225 when the PHY data unit 200 is a multi-userdata unit as compared to information included in the HE-SIG-A 225 whenthe PHY data unit 200 is a single-user data unit, in an embodiment. Inanother embodiment, different information is included in the HE-SIG-B230 when the PHY data unit 200 is a downlink data unit as compared tothe information is included in the HE-SIG-B 230 when the PHY data unit200 is an uplink data unit.

FIG. 3 is a diagram of a prior art frame exchange 300 between an AP andone or more client stations. In an embodiment, the frame exchange 300 isaccording to a legacy communication protocol. A client station transmitsPHY data units 302, 304, 306, and 308 to an AP. In an embodiment, PHYdata units 302, 304, 306, and 308 correspond to MAC protocol data units(MPDUs) within respective physical layer convergence protocol (PLCP)protocol data units (PPDUs) to the AP 14. In an embodiment, one or moreof the PHY data units 302, 304, 306, and 308 correspond to aggregatedMPDUs (A-MPDUs) transmitted in a PPDU to the AP 14.

Each of the PHY data units 302, 304, 306, and 308 includes an indicationof an acknowledgement policy to be followed by the AP 14 in response toreceiving the data units 302, 304, 306, and 308. The acknowledgementpolicy indication in a PHY data unit specifies when the AP shouldtransmit an acknowledgement in response to receiving the correspondingdata unit. In an embodiment, the acknowledgement policy indication isone of an immediate acknowledgement (ACK) request or a non-immediate ACKrequest. When the PHY data unit specifies an immediate ACK, the AP mustimmediately acknowledge the reception of the PHY data unit. On the otherhand, if the PHY data unit specifies a non-immediate ACK, the AP shouldacknowledge reception of the PHY data unit later (e.g., after receivingother PHY data units from the client station) in a block acknowledgment(BA) and only after receiving another PHY data unit that specifies animmediate ACK.

In an embodiment, the PHY data unit 302 includes an acknowledgementpolicy indication that requests an immediate ACK. In response toreceiving the PHY data unit 302, the AP 14 transmits an ACK frame 310after a suitable time period (e.g., a short interframe space (SIFS)).PHY data units 304 and 306 have an acknowledgment policy indication thatspecifies a non-immediate ACK. Therefore, the AP does not transmit anACK after either of the PHY data units 304, 306. PHY data unit 308includes an acknowledgement policy indication that requests an immediateACK. Therefore, in response to receiving data unit 308, the AP transmitsa BA frame 312 indicating the reception of the PHY data units 304, 306,and 308.

In the prior art procedure illustrated in FIG. 3, an AP can onlytransmit an ACK or a BA in response to receiving a data unit with theacknowledgement policy indication specifying an immediate ACK. If an AP,detects a missing MPDU in a block of MPDUs that specify thenon-immediate ACK, the AP cannot immediately inform the client stationof the missing MPDU. In addition, the AP is unable to release thereceived block of MPDUs in its receive buffer because there is a missingMPDU.

FIG. 4 is a diagram of an example multi-user frame exchange, accordingto an embodiment. A PHY data unit 400 corresponds to a trigger framethat prompts a multi-user uplink transmission, in an embodiment. The PHYdata unit 400 includes a preamble portion 402 and a data portion 404. Inan embodiment, the preamble portion 402 corresponds to a legacy preambleand conforms to a preamble format according to a legacy communicationprotocol, such as the IEEE 802.11a Standard, the IEEE 802.11n Standard,or the IEEE 802.11ac Standard, for example, in an embodiment. In anotherembodiment, the preamble 402 corresponds to a non-legacy preamble thatconforms to the IEEE 802.11ax Standard (now being developed), forexample, or conforming to another suitable communication protocol. Forexample, in an embodiment, the preamble portion 402 includes a preamblehaving a structure such as (e.g., the same as or similar to) thepreamble 204 of FIG. 2. At least some fields in the preamble portion 402are duplicated in each 20 MHz bandwidth portion of the data unit 400,according to some embodiments.

In an embodiment, the data portion 404 includes independent data formultiple client stations, in an embodiment. In an embodiment, the dataportion 404 includes data that is duplicated in multiple componentchannels (e.g., in multiple 20 MHz bandwidth portions), in anembodiment. In an embodiment, the data portion 404 includes a triggerframe that triggers an uplink OFDMA transmission 450 by a plurality ofclient stations 25. In an embodiment, the trigger frame includesinformation that indicates an allocation of sub-channels to be used forthe uplink OFDMA transmission 450, in an embodiment. The trigger framefurther indicates other transmission parameters to the multiple clientstations 25, such as which modulation and coding scheme (MCS) each ofthe client stations should use, an OFDM numerology (e.g., guardinterval, tone spacing, etc.) that each of the multiple client stationsshould use, transmit power that each of the multiple client stations 25should use, etc. In an embodiment, the trigger frame is a duplicatebroadcast frame transmitted to the multiple client stations 25 in each20 MHz component channel of the data unit 400. In another embodiment,the trigger frame is a broadcast frame that occupies the entirebandwidth of the data unit 400.

The data unit 450 includes a preamble portion 452 and a data portion454. In an embodiment, the preamble portion 452 includes a preamble suchas the preamble 204 of FIG. 2.

In an embodiment, the data portion 454 of the data unit 450 includes aplurality of MAC protocol data units (MPDUs) and/or aggregated MACprotocol data units (A-MPDUs) respectively directed to ones of multipleclient stations 25. In an embodiment, at least some of the MPDUs and/orA-MPDUs in the data portion 454 occupy sub-channels that span abandwidth smaller than a component channel bandwidth.

FIG. 5 is a diagram of an example transmission sequence 500 in a WLAN,such as the WLAN 10 of FIG. 1, according to an embodiment. In theexample illustrated in FIG. 5, an AP, such as the AP 14, triggers an ULOFDMA transmission by multiple client stations, such as multiple ones ofthe client stations 25, during a transmission opportunity period (TXOP)502. In an embodiment, the TXOP 502 is obtained by (e.g., based on asuitable channel assessment procedure, such as CSMA/CA), or scheduledby, the AP 14. At a time t1, the AP 14 transmits a trigger frame 504 toa plurality of client stations 25. In an embodiment, the trigger frame504 provides, to the plurality of client stations 25, resource unitallocation information and/or other transmission parameterscorresponding to a subsequent uplink OFDMA transmission during the TXOP502.

At time t2 each client station 25 participating in the UL OFDMAtransmission begins transmitting as part of the UL OFDMA transmission.In an embodiment, t2 begins upon expiration of a suitable predeterminedtime interval (e.g., a short inter-frame space (SIFS)) after completionof reception of the trigger frame 504 at the client stations 25. Inanother embodiment, a suitable predetermined time period other than SIFSis utilized.

The client stations 25 (STA0-STA3) transmit an uplink OFDMA transmission508, wherein the UL OFDMA transmission 508 includes PHY data units 506from respective stations 25. In an embodiment, each client stationtransmits a corresponding PHY data unit 506 starting at the time t2 in arespective sub-channel (e.g., comprising one or more RUs), allocated tothe client station 25, as indicated in the trigger frame 504, forexample. In an embodiment, each client station transmits a respectivePHY data unit 506 using transmission parameters, such as a modulationand coding scheme, a coding type, transmission power, length or durationof the data unit, etc. indicated in the trigger frame 504 In anotherembodiment, at least some of the client stations transmit PHY data units506 using at least some transmission parameters, such as a modulationand coding scheme, a coding type, transmission power, length or durationof the data unit, etc. determined by the client stations and notindicated in the trigger frame 504. In an embodiment, PHY data units 506include MPDUs and/or A-MPDUs transmitted from respective clientstations. In some embodiments and/or scenarios, a transmission in asub-channel in the UL OFDMA transmission 508 may be an MU-MIMOtransmission from multiple client stations 25, e.g., via multiplespatial streams.

In an embodiment, one or more MPDUs/A-MPDUs within the OFDMAtransmission 508 include an indication of acknowledgement policy to befollowed by the AP 14 in response to receiving the MPDUs/A-MPDUs. In anembodiment, one or more MPDUs/A-MPDUs within the OFDMA transmission 508include respective acknowledgement policy indications that requests animmediate ACK. In an embodiment, one or more MPDUs/A-MPDUs within theOFDMA transmission 508 include respective acknowledgement policyindications that request a non-immediate ACK.

At time t3, the AP transmits a DL OFDMA transmission 512, according toan embodiment. In another embodiment, the transmission 512 is a singleuser (SU) or broadcast transmission duplicated in multiple subchannels(e.g., component channels). In an embodiment, the SU or broadcasttransmission in each subchannel conforms to a legacy protocol. In anembodiment, time t3 begins upon expiration of a suitable predeterminedtime interval (such as a SIFS or some other suitable time period), aftercompletion of reception of the OFDMA transmission 508 at the AP 14, inan embodiment. In an embodiment, the DL OFDMA transmission 512 includesrespective ACK frames and/or BA frames 510 to the client stations 25(STA0 through STA3), acknowledging receipt of the PHY data units 506from the client stations 25. In an embodiment in which the transmission512 includes a SU or broadcast transmission duplicated in multiplesubchannels (e.g., component channels), the SU or broadcast transmission510 in each subchannel includes respective ACK frames and/or BA framesto the client stations 25 (STA0 through STA3), acknowledging receipt ofthe PHY data units 506 from the client stations 25. In an embodiment,each ACK/BA frame 510 is a broadcast acknowledgement frame that includesrespective acknowledgements for the client stations 25 (STA0 throughSTA3). In an embodiment, the broadcast acknowledgement frame is amulti-user block acknowledgement (M-BA) frame that includes respectiveblock acknowledgements for the respective client stations 25 (STA0through STA3).

In an embodiment, the AP is permitted to ignore the indication ofacknowledgement policy in an UL OFDMA transmission from a client station25, and thus the AP can act contrary to the indication ofacknowledgement policy in an UL OFDMA transmission. For example,according to an embodiment and in an illustrative scenario, when theindication of acknowledgement policy in the UL OFDMA transmission fromthe client station 25 specifies an immediate ACK, the AP instead doesnot immediately transmit an ACK to the client station 25, but rather theAP waits until one or more other UL OFDMA transmissions are received.This may be useful, for example, when only a minority of client stations25 (or even merely less than all client stations 25) participating in anUL OFDMA transmission requested immediate ACKs to the OFDMAtransmission, according to an embodiment. As another example, accordingto an embodiment and in another illustrative scenario, when theindication of acknowledgement policy in the UL OFDMA transmission fromthe client station 25 specifies a non-immediate ACK, the AP insteadimmediately transmits an ACK to the client station 25, rather thanwaiting until one or more other UL OFDMA transmissions are received.This may be useful, for example, when only a minority of client stations25 (or even merely less than all client stations 25) participating in anUL OFDMA transmission requested non-immediate ACKs to the OFDMAtransmission, according to an embodiment.

In another embodiment, the AP is not permitted to ignore the indicationof acknowledgement policy in an UL OFDMA transmission from a clientstation 25 when the client station 25 requests an immediate ACK; on theother hand, if the indication of acknowledgement policy specifies anon-immediate ACK, the AP can ignore the request and instead send animmediate ACK. For example, according to an embodiment and in anillustrative scenario, when the indication of acknowledgement policy inthe UL OFDMA transmission from the client station 25 specifies animmediate ACK, the AP must immediately transmit an ACK to the clientstation 25. As another example, according to an embodiment and inanother illustrative scenario, when the indication of acknowledgementpolicy in the UL OFDMA transmission from the client station 25 specifiesa non-immediate ACK, the AP instead immediately transmits an ACK to theclient station 25, rather than waiting until one or more other UL OFDMAtransmissions are received.

In some embodiments and/or scenarios, transmitting an immediateacknowledgement, even when a client station did not request an immediateacknowledgement, is advantageous by allowing an AP, such as the AP 14,to release MPDUs in a receive buffer, thereby reducing a buffer sizerequirement.

FIG. 6 is a diagram of an example transmission sequence 600 in a WLAN,such as the WLAN 10 of FIG. 1, according to an embodiment. In theexample transmission sequence 600, an AP, such as the AP 14, triggers anuplink OFDMA transmission by multiple client stations, such as multipleones of the client stations 25, during a TXOP 602.

At a time t1, the AP 14 transmits a trigger frame 604 to a plurality ofclient stations 25. In an embodiment, the trigger frame 604 provides, tothe plurality of client stations 25, resource unit allocationinformation and/or other transmission parameters corresponding to asubsequent uplink OFDMA transmission during the TXOP 602.

At time t2 each client station 25 participating in the UL OFDMAtransmission begins transmitting as part of the UL OFDMA transmission.In an embodiment, t2 begins upon expiration of a suitable predeterminedtime interval (e.g., SIFS) after completion of reception of the triggerframe 604 at the client stations 25. In another embodiment, a suitablepredetermined time period other than SIFS is utilized.

The client stations 25 (STA0-STA3) transmit an uplink OFDMA transmission608, wherein the UL OFDMA transmission 608 includes PHY data units 606from respective stations 25. The UL OFDMA transmission 608 is similar tothe UL OFDMA transmission 508 of FIG. 5 and will not be described indetail merely for purposes of brevity.

In an embodiment, one or more MPDUs/A-MPDUs 606 within the OFDMAtransmission 608 include an indication of acknowledgement policyregarding the AP 14 acknowledging receives of the MPDUs/A-MPDUs 606. Inan embodiment, one or more MPDUs/A-MPDUs 606 within the OFDMAtransmission 608 include respective acknowledgement policy indicationsthat requests an immediate ACK. In an embodiment, one or moreMPDUs/A-MPDUs 606 within the OFDMA transmission 608 include respectiveacknowledgement policy indications that request a non-immediate ACK.

In an embodiment, the AP does not transmit an immediate ACK responsivethe UL OFDMA transmission even though one or more MPDUs/A-MPDUs 606within the OFDMA transmission 608 include respective acknowledgementpolicy indications that requests an immediate ACK. Rather, at a time t3,the AP 14 transmits another trigger frame 610 to the plurality of clientstations 25. In an embodiment, the trigger frame 610 provides, to theplurality of client stations 25, resource unit allocation informationand/or other transmission parameters corresponding to a subsequentuplink OFDMA transmission during the TXOP 602.

At time t4 each client station 25 participating in the UL OFDMAtransmission begins transmitting as part of the UL OFDMA transmission.In an embodiment, t4 begins upon expiration of a suitable predeterminedtime interval (e.g., SIFS) after completion of reception of the triggerframe 610 at the client stations 25. In another embodiment, a suitablepredetermined time period other than SIFS is utilized.

In an embodiment, one or more MPDUs/A-MPDUs 612 within the OFDMAtransmission 614 include an indication of acknowledgement policyregarding the AP 14 acknowledging receives of the MPDUs/A-MPDUs 612. Inan embodiment, all MPDUs/A-MPDUs 612 within the OFDMA transmission 614include respective acknowledgement policy indications that requests animmediate ACK. In another embodiment, however, one or more MPDUs/A-MPDUs612 within the OFDMA transmission 614 include respective acknowledgementpolicy indications that request a non-immediate ACK.

At time t5, the AP transmits a DL OFDMA transmission 618, according toan embodiment. In another embodiment, the transmission 618 is a singleuser (SU) or broadcast transmission duplicated in multiple subchannels(e.g., component channels). In an embodiment, the SU or broadcasttransmission in each subchannel conforms to a legacy protocol. In anembodiment, time t5 begins upon expiration of a suitable predeterminedtime interval (such as a SIFS or some other suitable time period), aftercompletion of reception of the OFDMA transmission 614 at the AP 14, inan embodiment. In an embodiment, the DL OFDMA transmission 618 includesrespective ACK frames and/or BA frames 616 to the client stations 25(STA0 through STA3), acknowledging receipt of the PHY data units 606 and612 from the client stations 25. In an embodiment in which thetransmission 618 includes a SU or broadcast transmission duplicated inmultiple subchannels (e.g., component channels), the SU or broadcasttransmission 616 in each subchannel includes respective ACK framesand/or BA frames to the client stations 25 (STA0 through STA3),acknowledging receipt of the PHY data units 606 and 612 from the clientstations 25. In an embodiment, each ACK/BA frame 616 is a broadcastacknowledgement frame that includes respective acknowledgements for theclient stations 25 (STA0 through STA3). In an embodiment, the broadcastacknowledgement frame is a multi-user block acknowledgement (M-BA) framethat includes respective block acknowledgements for the respectiveclient stations 25 (STA0 through STA3).

In an embodiment, and in a scenario in which one or more MPDUs/A-MPDUs612 within the OFDMA transmission 614 include respective acknowledgementpolicy indications that request a non-immediate ACK, the AP transmits animmediate ACK responsive the UL OFDMA transmission 614 even though oneor more MPDUs/A-MPDUs 612 within the OFDMA transmission 614 includerespective acknowledgement policy indications that requests anon-immediate ACK.

In an embodiment, more than one downlink OFDMA transmission can be usedfor acknowledgement of a single UL OFDMA transmission. FIG. 7 is adiagram of an example transmission sequence 700 in a WLAN, such as theWLAN 10 of FIG. 1, according to an embodiment, in which an AP, such asthe AP 14, triggers an uplink OFDMA transmission by multiple clientstations, such as multiple ones of the client stations 25, during TXOP702. At a time t1, the AP 14 transmits a trigger frame 704 to aplurality of client stations 25. In an embodiment, the trigger frame 704is similar to trigger frame 504 and/or the trigger frame 604, and is notdiscussed in detail for purposes of brevity.

At a time t2, client stations 25 (e.g., STA0 to STA11) transmit an ULOFDMA transmission 708, wherein the UL OFDMA transmission 708 includesPHY data units 706. In an embodiment, the UL OFDMA transmission 708 issimilar to the UL OFDMA transmission 508 and/or the UL OFDMAtransmission 708, and is not discussed in detail for purposes ofbrevity. In an embodiment, the UL OFDMA transmission 708 includestransmissions from a number of client stations 25 that is greater than amaximum number of client stations than can be acknowledged in a singleDL OFDMA acknowledgment frame. As an illustrative example, according toan illustrative embodiment, a communication protocol defines a DL OFDMAACK frame that can be used to acknowledge transmissions from at mostnine client stations, whereas the UL OFDMA transmission 708 includestransmissions from more than nine client stations.

Therefore, in an embodiment, the AP 14 acknowledges the UL OFDMAtransmission 708 with multiple DL OFDMA ACK frames. For example, at atime t3, the AP 14 transmits respective BA frames in a first downlinkOFDMA ACK frame 714 to respective client stations 25, in response toreceiving the uplink OFDMA transmission 708, but only a subset of clientstations (e.g., STA0 through STA8) that participated in the uplink OFDMAtransmission 708 are acknowledged in the downlink OFDMA ACK frame 714.For instance, in an embodiment, whereas the UL OFDMA data transmission708 included transmissions from twelve client stations (STA0-STA11), thedownlink OFDMA ACK frame 714 acknowledges transmissions of only nineclient stations (e.g., STA0 to STA8).

At a time t4, the AP 14 transmits respective BA frames in a seconddownlink OFDMA ACK frame 718 to respective client stations 25, also inresponse to receiving the uplink OFDMA transmission 708, but anothersubset of client stations (e.g., STA9 through STA11) that participatedin the uplink OFDMA transmission 708 are acknowledged in the downlinkOFDMA ACK frame 718. In an embodiment, t4 begins upon expiration of asuitable predetermined time interval (e.g., SIFS) after completion oftransmission of the downlink OFDMA ACK frame 714. In another embodiment,a suitable predetermined time period other than SIFS is utilized.

In an embodiment, whereas the UL OFDMA data transmission 708 includedtransmissions from twelve client stations (STA0-STA11), and whereas thedownlink OFDMA ACK frame 714 acknowledged transmissions of nine clientstations (e.g., STA0 to STA8), the downlink OFDMA ACK frame 718acknowledges transmissions of three client stations (e.g., STA9 toSTA11).

In another embodiment, when a UL OFDMA transmission includestransmissions from a number of client stations 25 that is greater than amaximum number of client stations than can be acknowledged in a singleDL OFDMA acknowledgment frame, the AP 14 is configured to transmit abroadcast acknowledgement frame that includes respectiveacknowledgements for the client stations 25 (e.g., STA0 through STA11).In an embodiment, the broadcast acknowledgement frame is an M-BA framethat includes respective block acknowledgements for the respectiveclient stations 25 (e.g., STA0 through STA11).

In another embodiment, when a UL OFDMA transmission includestransmissions from a number of client stations 25 that is greater than amaximum number of client stations than can be acknowledged in a DL OFDMAacknowledgment frame, the AP utilizes MU-MIMO to acknowledge the ULOFDMA transmissions. FIG. 8 is a diagram of an example transmissionsequence 800 in a WLAN, such as the WLAN 10 of FIG. 1, according to anembodiment, in which an AP, such as the AP 14, triggers an uplink OFDMAtransmission by multiple client stations, such as multiple ones of theclient stations 25, during a TXOP 802. The example transmission sequence800 is similar to the example transmission sequence 700 of FIG. 7, andlike-numbered elements are not described in detail for purposes ofbrevity.

At a time t1, the AP 14 transmits a trigger frame 704 to a plurality ofclient stations 25. At time t2, the client stations 25 transmit anuplink OFDMA transmission 708, wherein the uplink OFDMA transmission 708includes PHY data units 706.

At a time t3, the AP 14 transmits a BA transmission 810 in a downlinkOFDMA transmission 812 to client stations 25, in response to receivingthe uplink OFDMA transmission 708. In an embodiment, the AP transmitseach of BA frames 814 using MU MIMO (e.g., using spatial divisionmultiple access (SDMA)) to transmit different BA frames to multipleclient stations over a single sub-channel. For instance, in anembodiment, BA 814-1 is comprised of multiple transmissions to multipleclient stations, each transmission over a different spatial stream toacknowledge uplink OFDMA transmission 706-0 from multiple clientstations 25 (e.g., STA0 to STA3). In an embodiment, use of SDMAtechniques requires downlink MU MIMO beamforming training between the AP14 and the stations to receive the SDMA transmissions.

In an embodiment, BA transmissions 818 do not utilize MU-MIMO.

FIG. 9 is a flow diagram of an example method 1100 for acknowledging anuplink OFDMA transmission, according to an embodiment. In someembodiments, the method 1100 is implemented by the AP 14 (FIG. 1). Forexample, in some embodiments, the network interface device 16 isconfigured to implement the method 1100. In other embodiments, anothersuitable network interface device is configured to implement the method1100.

At block 1104, an uplink OFDMA transmission is received. In anembodiment, the uplink OFDMA transmission includes respectivetransmissions from multiple communication devices. In an embodiment, therespective transmissions from the multiple communication devices aretransmitted in respective frequency portions (e.g., in respectivecomponent channels). In an embodiment, the respective transmissions fromthe multiple communication devices include indications of respectiveacknowledgement policies corresponding to the respective transmissions.

At block 1108, one or more OFDMA acknowledgment PHY data units toacknowledge the uplink OFDMA transmission are generated. In anembodiment, the one or more OFDMA acknowledgment PHY data units do notcomply with at least one of the acknowledgment policies corresponding tothe uplink OFDMA transmission.

At block 1112, the one or more OFDMA acknowledgment PHY data units aretransmitted to acknowledge the uplink OFDMA transmission, or the one ormore OFDMA acknowledgment PHY data units are caused to be transmitted.For example, logic circuitry and/or a processor executing machinereadable instructions causes one or more transceivers to transmit theone or more OFDMA acknowledgment PHY data units generated at block 1108.

In an embodiment, one of the acknowledgment policies specifies that atransmission from one of the second communication devices, is to beimmediately acknowledged, and the one or more OFDMA acknowledgment PHYdata units are generated and/or transmitted such that the uplink OFDMAtransmission is not immediately acknowledged. For example, in anembodiment, the AP transmits another PHY data unit that does notacknowledge the uplink OFDMA transmission, prior to transmitting the oneor more OFDMA acknowledgment PHY data units that acknowledge the uplinkOFDMA transmission.

In an embodiment, one of the acknowledgment policies specifies that atransmission from one of the second communication devices, is not to beimmediately acknowledged, but the one or more OFDMA acknowledgment PHYdata units are generated and/or transmitted such that the uplink OFDMAtransmission is immediately acknowledged. For example, in an embodiment,the AP transmits the one or more OFDMA acknowledgment PHY data unitsprior to the AP transmitting any other PHY data unit that does notacknowledge the uplink OFDMA transmission.

In an embodiment, the one or more OFDMA acknowledgment PHY data unitsare generated to include a PHY data unit that includes multipleacknowledgment frames in respective component channels.

In an embodiment, the one or more OFDMA acknowledgment PHY data unitsare generated to include multiple acknowledgment frames in a singlecomponent channel using spatial division multiple access (SDMA).

In an embodiment, the one or more OFDMA acknowledgment PHY data unitsare generated to include a broadcast acknowledgement frame, thebroadcast acknowledgment frame indicating respective blockacknowledgements for multiple second communication devices.

In an embodiment, the broadcast acknowledgement frame is an M-BA frame.

In an embodiment, the one or more OFDMA acknowledgment PHY data unitsare generated to include at least: a first OFDMA acknowledgment PHY dataunit to acknowledge one or more respective transmissions in the uplinkOFDMA transmission from a first set of one or more second communicationdevices; and a second OFDMA acknowledgment PHY data unit to acknowledgeone or more respective transmissions in the uplink OFDMA transmissionfrom a second set of one or more second communication devices.

In an embodiment, transmitting the one or more OFDMA acknowledgment PHYdata units comprises: transmitting the first OFDMA acknowledgment PHYdata unit; and after completion of transmitting first OFDMAacknowledgment PHY data unit, transmitting the second OFDMAacknowledgment PHY data unit.

In various embodiments, the method 900 is performed in a manner similarto those described in connection with FIGS. 5-8, or in another suitablemanner.

In an embodiment, a method for communicating in a wireless communicationnetwork includes: receiving, at the first communication device, anuplink orthogonal frequency multiple access (OFDMA) transmission,wherein the uplink OFDMA transmission includes respective transmissionsfrom the multiple second communication devices, wherein the respectivetransmissions from the multiple second communication devices includeindications of respective acknowledgment policies corresponding to therespective transmissions from the multiple second communication devices;generating, at the first communication device, one or moreacknowledgment physical layer (PHY) data units to acknowledge at least aportion of the uplink OFDMA transmission, wherein the one or moreacknowledgment PHY data units do not comply with at least one of theacknowledgment policies corresponding to the uplink OFDMA transmission;and transmitting, with the first communication device, the one or moreacknowledgment PHY data units to acknowledge the at least the portion ofthe uplink OFDMA transmission.

In other embodiments, the method includes one of, or any suitablecombination of two or more of the following features.

One of the acknowledgment policies specifies that a transmission,included in the OFDMA transmission, from one of the second communicationdevices, is to be immediately acknowledged; and the method furthercomprises: transmitting, with the first communication device, anotherPHY data unit that does not acknowledge the uplink OFDMA transmission,prior to transmitting, with the first communication device, the one ormore acknowledgment PHY data units that acknowledge the at least theportion of the uplink OFDMA transmission.

One of the acknowledgment policies specifies that a transmission,included in the OFDMA transmission, from one of the second communicationdevices, is not to be immediately acknowledged; and the one or moreacknowledgment PHY data units are transmitted to immediately acknowledgeat least the portion of the uplink OFDMA transmission.

The first communication device transmits the one or more acknowledgmentPHY data units prior to the first communication device transmitting anyother PHY data unit that does not acknowledge any portion of the uplinkOFDMA transmission.

Generating the one or more acknowledgment PHY data units comprises:generating a PHY data unit that includes multiple acknowledgment framesin respective component channels.

Generating the one or more acknowledgment PHY data units furthercomprises: generating the PHY data unit to include multipleacknowledgment frames in a single component channel using spatialdivision multiple access (SDMA).

Generating the one or more acknowledgment PHY data units comprises:generating a PHY data unit that includes a broadcast acknowledgementframe, the broadcast acknowledgment frame indicating respective blockacknowledgements for multiple second communication devices.

The broadcast acknowledgement frame is a multi-user blockacknowledgement (M-BA) frame.

Generating the one or more acknowledgment PHY data units comprisesgenerating at least: a first acknowledgment PHY data unit to acknowledgeone or more respective transmissions in the uplink OFDMA transmissionfrom a first set of one or more second communication devices; and asecond acknowledgment PHY data unit to acknowledge one or morerespective transmissions in the uplink OFDMA transmission from a secondset of one or more second communication devices.

Transmitting the one or more acknowledgment PHY data units comprises:transmitting the first acknowledgment PHY data unit; and aftercompletion of transmitting first acknowledgment PHY data unit,transmitting the second acknowledgment PHY data unit.

Generating the one or more acknowledgment PHY data units comprises oneof: generating an OFDMA PHY data unit; generating a single user PHY dataunit duplicated in a plurality of component channels; and generating abroadcast PHY data unit duplicated in the plurality of componentchannels.

In another embodiment, an apparatus comprises a network interface deviceassociated with a first communication device. The network interfacedevice includes one or more integrated circuits configured to: receivean uplink orthogonal frequency multiple access (OFDMA) transmission,wherein the uplink OFDMA transmission includes respective transmissionsfrom multiple second communication devices, wherein the respectivetransmissions from the multiple second communication devices includeindications of respective acknowledgment policies corresponding to therespective transmissions from the multiple second communication devices;generate one or more OFDMA acknowledgment physical layer (PHY) dataunits to acknowledge at least a portion of the uplink OFDMAtransmission, wherein the one or more OFDMA acknowledgment PHY dataunits do not comply with at least one of the acknowledgment policiescorresponding to the uplink OFDMA transmission; and cause the firstcommunication device to transmit the one or more OFDMA acknowledgmentPHY data units to acknowledge the at least the portion of the uplinkOFDMA transmission.

In other embodiments, the apparatus includes one of, or any suitablecombination of two or more of the following features.

One of the acknowledgment policies specifies that a transmission,included in the OFDMA transmission, from one of the second communicationdevices, is to be immediately acknowledged; and the one or moreintegrated circuits are configured to: cause the first communicationdevice to transmit another PHY data unit that does not acknowledge theuplink OFDMA transmission, prior to transmitting, with the firstcommunication device, the one or more acknowledgment PHY data units thatacknowledge the at least the portion of the uplink OFDMA transmission.

One of the acknowledgment policies specifies that a transmission,included in the OFDMA transmission, from one of the second communicationdevices, is not to be immediately acknowledged; and the one or moreintegrated circuits are configured to cause the first communicationdevice to transmit the one or more acknowledgment PHY data units toimmediately acknowledge the at least the portion of the uplink OFDMAtransmission.

The one or more integrated circuits are configured to cause the firstcommunication device to transmit the one or more acknowledgment PHY dataunits prior to the first communication device transmitting any other PHYdata unit that does not acknowledge any portion of the uplink OFDMAtransmission.

The one or more integrated circuits are further configured to: generatean acknowledgment PHY data unit that includes multiple acknowledgmentframes in respective component channels.

The one or more integrated circuits are further configured to: generatethe acknowledgment PHY data unit to include multiple acknowledgmentframes in a single component channel using spatial division multipleaccess (SDMA).

The one or more integrated circuits are further configured to:generating an acknowledgment PHY data unit that includes a broadcastacknowledgement frame, the broadcast acknowledgment frame indicatingrespective block acknowledgements for multiple second communicationdevices.

The broadcast acknowledgement frame is a multi-user blockacknowledgement (M-BA) frame.

The one or more integrated circuits are further configured to generate:a first acknowledgment PHY data unit to acknowledge one or morerespective transmissions in the uplink OFDMA transmission from a firstset of one or more second communication devices; and a secondacknowledgment PHY data unit to acknowledge one or more respectivetransmissions in the uplink OFDMA transmission from a second set of oneor more second communication devices.

The one or more integrated circuits are further configured to cause thefirst communication device to: transmit the first acknowledgment PHYdata unit; and after completion of transmitting first OFDMAacknowledgment PHY data unit, transmit the second acknowledgment PHYdata unit.

The one or more integrated circuits are further configured to, one of:generate an OFDMA PHY data unit; generate a single user PHY data unitduplicated in a plurality of component channels; or generate a broadcastPHY data unit duplicated in the plurality of component channels.

The network interface device comprises: a plurality of transceiversimplemented at least partially on the one or more integrated circuitdevices.

The apparatus further comprises a plurality of antennas coupled to theplurality of transceivers.

At least some of the various blocks, operations, and techniquesdescribed above may be implemented utilizing hardware, a processorexecuting firmware instructions, a processor executing softwareinstructions, or any combination thereof. When implemented utilizing aprocessor executing software or firmware instructions, the software orfirmware instructions may be stored in/on a computer readable medium ormedia, such as a RAM, a ROM, a flash memory, memory of a processor, amagnetic disk, an optical disk, a magnetic tape, etc. The software orfirmware instructions may include machine readable instructions that,when executed by one or more processors, cause the one or moreprocessors to perform various acts.

When implemented in hardware, the hardware may comprise one or more ofdiscrete components, one or more integrated circuits, one or moreapplication-specific integrated circuits (ASICs), one or moreprogrammable logic devices (PLDs), etc.

While the present invention has been described with reference tospecific examples, which are intended to be illustrative only and not tobe limiting of the invention, changes, additions and/or deletions may bemade to the disclosed embodiments without departing from the scope ofthe invention.

What is claimed is:
 1. A method for communicating in a wirelesscommunication network, the method comprising: receiving, at the firstcommunication device, an uplink orthogonal frequency multiple access(OFDMA) transmission, wherein the uplink OFDMA transmission includesrespective data units from multiple second communication devices,wherein the respective data units include respective indications ofrespective acknowledgment policies corresponding to the respective dataunits, wherein a first acknowledgement policy among the respectiveacknowledgment policies indicates that a first data unit, among therespective data units, is to be acknowledged prior to any subsequenttransmission from any of the multiple second communication devices, andwherein a second acknowledgement policy among the respectiveacknowledgment policies indicates that a second data unit, among therespective data units, is to be acknowledged only after thecorresponding second communication device has transmitted a subsequentdata unit in a subsequent uplink OFDMA transmission; generating, at thefirst communication device, an acknowledgment physical layer (PHY) dataunit to acknowledge at least the first data unit and the second dataunit; and transmitting, with the first communication device, theacknowledgment PHY data unit in a downlink transmission to acknowledgeat least the first data unit and the second data unit, including one of:i) transmitting the downlink transmission prior to any subsequenttransmission from any of the multiple second communication devices, orii) transmitting the downlink transmission only after receiving thesubsequent uplink OFDMA transmission.
 2. The method of claim 1, whereintransmitting the acknowledgment PHY data unit in the downlinktransmission comprises: ignoring, by the first communication device, thesecond acknowledgement policy indicating that the second data unit is tobe acknowledged only after the corresponding second communication devicehas transmitted the subsequent data unit in the subsequent uplink OFDMAtransmission; and transmitting the downlink transmission prior to thecorresponding second communication device transmitting the subsequentdata unit in the subsequent uplink OFDMA transmission.
 3. The method ofclaim 2, wherein transmitting the acknowledgment PHY data unit in thedownlink transmission comprises: beginning the downlink transmission ata predetermined time period after an end of the uplink OFDMAtransmission.
 4. The method of claim 3, wherein the firstacknowledgement policy indicates that the first data unit is to beacknowledged beginning at the predetermined time period after the end ofthe uplink OFDMA transmission.
 5. The method of claim 1, whereintransmitting the acknowledgment PHY data unit in the downlinktransmission comprises: ignoring, by the first communication device, thefirst acknowledgement policy indicating that the first data unit is tobe acknowledged prior to any subsequent transmission from any of themultiple second communication devices; and transmitting the downlinktransmission only after receiving the subsequent uplink OFDMAtransmission.
 6. The method of claim 1, wherein generating theacknowledgment PHY data unit comprises: generating the acknowledgmentPHY data unit to include multiple acknowledgment frames in respectivecomponent channels.
 7. The method of claim 6, wherein generating theacknowledgment PHY data unit further comprises: generating theacknowledgment PHY data unit to include multiple acknowledgment framesin a single component channel using spatial division multiple access(SDMA).
 8. The method of claim 1, wherein generating the acknowledgmentPHY data unit comprises: generating the acknowledgment PHY data unit toinclude a broadcast acknowledgement frame, the broadcast acknowledgmentframe indicating respective block acknowledgements for multiple secondcommunication devices.
 9. The method of claim 8, wherein the broadcastacknowledgement frame is a multi-user block acknowledgement (M-BA)frame.
 10. The method of claim 1, wherein generating the acknowledgmentPHY data unit comprises generating at least: a first acknowledgment PHYdata unit to acknowledge one or more respective transmissions in theuplink OFDMA transmission from a first set of one or more secondcommunication devices; and a second acknowledgment PHY data unit toacknowledge one or more respective transmissions in the uplink OFDMAtransmission from a second set of one or more second communicationdevices.
 11. A wireless communication device, comprising: a wirelessnetwork interface device associated with a first communication device,wherein the wireless network interface device includes one or moreintegrated circuits (ICs) configured to: receive an uplink orthogonalfrequency multiple access (OFDMA) transmission, wherein the uplink OFDMAtransmission includes respective data units from multiple secondcommunication devices, wherein the respective data units includerespective indications of respective acknowledgment policiescorresponding to the respective data units, wherein a firstacknowledgement policy among the respective acknowledgment policiesindicates that a first data unit, among the respective data units, is tobe acknowledged prior to any subsequent transmission from any of themultiple second communication devices, and wherein a secondacknowledgement policy among the respective acknowledgment policiesindicates that a second data unit, among the respective data units, isto be acknowledged only after the corresponding second communicationdevice has transmitted a subsequent data unit in a subsequent uplinkOFDMA transmission, generate an acknowledgment physical layer (PHY) dataunit to acknowledge at least the first data unit and the second dataunit, and transmit the acknowledgment PHY data unit in a downlinktransmission to acknowledge at least the first data unit and the seconddata unit, including one of: i) transmitting the downlink transmissionprior to any subsequent transmission from any of the multiple secondcommunication devices, or ii) transmitting the downlink transmissiononly after receiving the subsequent uplink OFDMA transmission.
 12. Thewireless communication device of claim 11, wherein the one or more ICsare further configured to: ignore the second acknowledgement policyindicating that the second data unit is to be acknowledged only afterthe corresponding second communication device has transmitted thesubsequent data unit in the subsequent uplink OFDMA transmission; andtransmit the downlink transmission prior to the corresponding secondcommunication device transmitting the subsequent data unit in thesubsequent uplink OFDMA transmission.
 13. The wireless communicationdevice of claim 12, wherein the one or more ICs are further configuredto: begin the downlink transmission at a predetermined time period afteran end of the uplink OFDMA transmission.
 14. The wireless communicationdevice of claim 13, wherein the first acknowledgement policy indicatesthat the first data unit is to be acknowledged beginning at thepredetermined time period after the end of the uplink OFDMAtransmission.
 15. The wireless communication device of claim 11, whereinthe one or more ICs are further configured to: ignore the firstacknowledgement policy indicating that the first data unit is to beacknowledged prior to any subsequent transmission from any of themultiple second communication devices; and transmit the downlinktransmission only after receiving the subsequent uplink OFDMAtransmission.
 16. The wireless communication device of claim 11, whereinthe one or more ICs are further configured to: generate theacknowledgment PHY data unit to include multiple acknowledgment framesin respective component channels.
 17. The wireless communication deviceof claim 16, wherein the one or more ICs are further configured to:generate the acknowledgment PHY data unit to include multipleacknowledgment frames in a single component channel using spatialdivision multiple access (SDMA).
 18. The wireless communication deviceof claim 11, wherein the one or more ICs are further configured to:generate the acknowledgment PHY data unit to include a broadcastacknowledgement frame, the broadcast acknowledgment frame indicatingrespective block acknowledgements for multiple second communicationdevices.
 19. The wireless communication device of claim 18, wherein thebroadcast acknowledgement frame is a multi-user block acknowledgement(M-BA) frame.
 20. The wireless communication device of claim 11, whereinthe one or more ICs are further configured to generate theacknowledgment PHY data unit comprises at least be generating: a firstacknowledgment PHY data unit to acknowledge one or more respectivetransmissions in the uplink OFDMA transmission from a first set of oneor more second communication devices; and a second acknowledgment PHYdata unit to acknowledge one or more respective transmissions in theuplink OFDMA transmission from a second set of one or more secondcommunication devices.